C++ 右键单击Qt中的事件以打开关联菜单

我有一段代码调用mousePressEvent。我用鼠标左键单击输出光标的坐标，用鼠标右键单击也可以，但我也想用鼠标右键单击打开上下文菜单。到目前为止，我掌握的代码是：

void plotspace::mousePressEvent(QMouseEvent*event)
{
    double trange = _timeonright - _timeonleft;
    int twidth = width();
    double tinterval = trange/twidth;

    int xclicked = event->x();

    _xvaluecoordinate = _timeonleft+tinterval*xclicked;



    double fmax = Data.plane(X,0).max();
    double fmin = Data.plane(X,0).min();
    double fmargin = (fmax-fmin)/40;
    int fheight = height();
    double finterval = ((fmax-fmin)+4*fmargin)/fheight;

    int yclicked = event->y();

    _yvaluecoordinate = (fmax+fmargin)-finterval*yclicked;

    cout<<"Time(s): "<<_xvaluecoordinate<<endl;
    cout<<"Flux: "<<_yvaluecoordinate<<endl;
    cout << "timeonleft= " << _timeonleft << "\n";

    returncoordinates();

    emit updateCoordinates();

    if (event->button()==Qt::RightButton)
    {
            contextmenu->setContextMenuPolicy(Qt::CustomContextMenu);

            connect(contextmenu, SIGNAL(customContextMenuRequested(const QPoint&)),
            this, SLOT(ShowContextMenu(const QPoint&)));

            void A::ShowContextMenu(const QPoint &pos) 
            {
                QMenu *menu = new QMenu;
                menu->addAction(tr("Remove Data Point"), this,  
                SLOT(test_slot()));

                menu->exec(w->mapToGlobal(pos));
            }

    }   

}

void plotspace:：mousePressEvent（QMouseEvent*event）
{
双重交易=_timeonright-_timeonleft；
int twidth=宽度（）；
双t=交易量/分次；
int xclicked=event->x（）；
_xvaluecoordinate=\u timeonleft+tinterval*xclicked；
double fmax=Data.plane（X，0.max（）；
double fmin=Data.plane（X，0.min（）；
双fmargin=（fmax-fmin）/40；
int fheight=高度（）；
双finterval=（（fmax-fmin）+4*fmargin）/fheight；
int yclicked=event->y（）；
_yvaluecoordinate=（fmax+fmargin）-finterval*yclicked；
当小部件的contextMenuPolicy为
Qt:：customContextMenuRequested
且用户已请求小部件上的上下文菜单时，将发出
customContextMenuRequested
，因此在小部件的构造函数中，您可以调用
setContextMenuPolicy
并将
customContextMenuRequested
连接到插槽以创建cus汤姆上下文菜单

在
绘图空间的构造函数中
：

this->setContextMenuPolicy(Qt::CustomContextMenu);

connect(this, SIGNAL(customContextMenuRequested(const QPoint &)), 
        this, SLOT(ShowContextMenu(const QPoint &)));

ShowContextMenu
插槽应该是
plotspace
的类成员，如：

void plotspace::ShowContextMenu(const QPoint &pos) 
{
   QMenu contextMenu(tr("Context menu"), this);

   QAction action1("Remove Data Point", this);
   connect(&action1, SIGNAL(triggered()), this, SLOT(removeDataPoint()));
   contextMenu.addAction(&action1);

   contextMenu.exec(mapToGlobal(pos));
}